U.S. patent application number 16/840115 was filed with the patent office on 2021-10-07 for system and method for scanning pattern optimization for flash therapy treatment planning.
The applicant listed for this patent is Varian Medical Systems International AG., Varian Medical Systems, Inc., Varian Medical Systems Particle Therapy GmbH.. Invention is credited to Eric ABEL, Michiko ALCANZARE, Michael FOLKERTS, Adam Harrington, Timo KOPONEN, Anthony MAGLIARI, Jessica PEREZ, Christel SMITH, Reynald VANDERSTRAETEN.
Application Number | 20210308486 16/840115 |
Document ID | / |
Family ID | 1000004903780 |
Filed Date | 2021-10-07 |
United States Patent
Application |
20210308486 |
Kind Code |
A1 |
PEREZ; Jessica ; et
al. |
October 7, 2021 |
SYSTEM AND METHOD FOR SCANNING PATTERN OPTIMIZATION FOR FLASH
THERAPY TREATMENT PLANNING
Abstract
Embodiments of the present invention provide methods and systems
for proton therapy planning that maximize the dose rate for
different target sizes for FLASH therapy treatment are disclosed
herein according to embodiments of the present invention. According
to embodiments, non-standard scanning patterns can be generated,
for example, using a TPS optimizer, to maximize dose rate and the
overall FLASH effect for specific volumes at risk. The novel
scanning patterns can include scanning subfields of a field that
are scanned independently or spiral-shaped patterns, for example.
In general, spot locations and beam paths between spots are
optimized to substantially achieve a desired dose rate in defined
regions of the patient's body for FLASH therapy treatment.
Inventors: |
PEREZ; Jessica; (Genevea,
CH) ; ABEL; Eric; (San Jose, CA) ; FOLKERTS;
Michael; (Carrollton, TX) ; SMITH; Christel;
(Santa Barbara, CA) ; Harrington; Adam; (US)
; KOPONEN; Timo; (Espoo, FI) ; VANDERSTRAETEN;
Reynald; (Uccle, BE) ; MAGLIARI; Anthony;
(Newark, IL) ; ALCANZARE; Michiko; (Espoo,
FI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Varian Medical Systems, Inc.
Varian Medical Systems Particle Therapy GmbH.
Varian Medical Systems International AG. |
Palo Alto
Troisdorf
Cham |
CA |
US
DE
CH |
|
|
Family ID: |
1000004903780 |
Appl. No.: |
16/840115 |
Filed: |
April 3, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61N 5/1031 20130101;
A61N 5/1007 20130101; A61N 2005/1087 20130101; A61N 2005/1012
20130101 |
International
Class: |
A61N 5/10 20060101
A61N005/10 |
Claims
1. A system for proton therapy treatment, comprising: a gantry
comprising a nozzle configured to emit a controllable proton beam;
a proton therapy treatment system that controls the gantry
according to a treatment plan; and a treatment planning system
comprising: a memory for storing image data and the treatment plan;
and a processor operable to perform a method of generating the
treatment plan, the method comprising: receiving imaging data of a
target volume; dividing the imaging data of the target volumes into
a scanning pattern comprising a plurality of subfields comprising a
first scanning direction and a second scanning direction;
optimizing the scanning pattern to achieve a desired dose rate; and
outputting a treatment plan comprising the scanning pattern,
wherein the treatment plan is operable to instruct a proton therapy
treatment system to perform proton therapy treatment on the target
volume according to the scanning pattern, and wherein further the
proton therapy treatment system, in accordance with the treatment
plan, scans in the first scanning direction at a faster scanning
rate, and scans in the second scanning direction at a slower
scanning rate, and wherein the treatment plan is a proton therapy
treatment plan.
2. The system as recited in claim 1, wherein the method further
comprises performing proton therapy treatment using the proton
therapy treatment system according to the optimized proton therapy
treatment plan.
3. The system as recited in claim 1, wherein the method further
comprises receiving the desired dose rate as input.
4. The system as recited in claim 1, wherein the method further
comprises determining the desired dose rate according to machine
parameters associated with the proton therapy treatment system.
5. The system as recited in claim 1, wherein the plurality of
subfields is scanned independently by the proton therapy treatment
system.
6. The system as recited in claim 1, wherein the dividing the
imaging data of the target volume into a scanning pattern
comprising a plurality of subfields is performed based on at least
one of: a size of the target volume; a shape of the target volume;
and a location of the target volume.
7. The system as recited in claim 1, wherein the desired dose rate
is a upper limit dose rate of the proton therapy treatment
system.
8. A method of proton therapy treatment, the method comprising:
receiving imaging data of a target volume; dividing the imaging
data of the target volume into a scanning pattern comprising a
plurality of subfields, the plurality of subfields comprising a
first scanning direction and a second scanning direction;
optimizing the scanning pattern to achieve a desired dose rate; and
outputting a proton therapy treatment plan comprising the scanning
pattern, wherein the proton therapy treatment plan is operable to
instruct a proton therapy treatment system to perform proton
therapy treatment according to the scanning pattern, and wherein
further the proton therapy treatment system is operable to scan in
the first scanning direction at a faster scanning rate, and
operable to scan in the second scanning direction at a slower
scanning rate.
9. The method as recited in claim 8, further comprising performing
proton therapy treatment using the proton therapy treatment system
according to the proton therapy treatment plan.
10. The method as recited in claim 8, further comprising receiving
the desired dose rate as input.
11. The method as recited in claim 8, further comprising
determining the desired dose rate according to machine parameters
associated with the proton therapy treatment system.
12. The method as recited in claim 8, wherein the plurality of
subfields is scanned independently by the proton therapy treatment
system.
13. The method as recited in claim 8, wherein the dividing the
imaging data of the target volume into a scanning pattern
comprising a plurality of subfields is performed based on at least
one of: a size of the target volume; a shape of the target volume;
and a location of the target volume.
14. The method as recited in claim 8, wherein the desired dose rate
is an upper limit dose rate of the proton therapy system.
15. A method for proton therapy treatment, the method comprising:
receiving imaging data of a target volume of a patient; determining
a size of the target volume based on the imaging data; generating a
scanning pattern based on the size of the target volume; optimizing
the scanning pattern to reduce to a lower threshold limit an amount
of radiation received by healthy tissue of the patient, wherein the
scanning pattern comprises a substantially spiral-shaped scanning
pattern; and outputting a proton therapy treatment plan comprising
the scanning pattern, wherein the proton therapy treatment plan is
operable to instruct a proton therapy treatment system to perform
proton therapy treatment according to the scanning pattern.
16. The method as recited in claim 15, further comprising
performing proton therapy treatment using the proton therapy
treatment system according to the treatment plan.
17. The method as recited in claim 15, wherein the scanning pattern
is aligned to a grid-shaped pattern.
18. The method as recited in claim 15, wherein the scanning pattern
is not aligned to a grid-shaped pattern.
19. The method as recited in claim 15, wherein the proton therapy
treatment plan comprises performing FLASH proton therapy.
20. The method as recited in claim 15, wherein the proton therapy
treatment system is configured for pencil beam scanning.
Description
FIELD
[0001] Embodiments of the present invention relate generally to the
field of radiotherapy treatment. More specifically, embodiments of
the present invention relate to systems and methods for proton
therapy treatment planning and generating scanning patterns.
BACKGROUND
[0002] Particle therapy using protons or other ions is a type of
radiotherapy that uses an external beam to provide targeted
ionizing radiation to a tumor. Protons or other positively charged
ions are sent to an accelerator to bring the particles' energy to a
predetermined value. The protons or other ions then move through a
beam-transport system, where magnets are used to shape, focus
and/or direct the proton or other ion beam as necessary.
[0003] Standard radiation therapy deposits energy in "spots" along
the path of the beam to a target tumor. However, the reach of the
energy also extends beyond the tissues of the target tumor, and may
deliver radiation to healthy tissue around the tumor site. This
excess radiation may damage normal tissue or organs near the target
area. Moreover, the selection of specific energies and the number
of spots is decided based only on patient geometry and hardware
constraints. The subsequent optimization to achieve the dosimetric
criteria for treatment is traditionally performed only on spot
intensities, which can produce less than optimal results.
[0004] Radiation treatment plans can be optimized according to
given dose volume constraints for target volume and organs at risk
and according to plan robustness using commercially available
treatment planning systems. Dose distributions are calculated using
beam characteristics and a machine specific dose calibration.
However, machine or system limitations can lead to translation of
an aimed dose distribution into machine/treatment delivery system
parameters that generate an unacceptable or suboptimal treatment
plan. For example, the generated treatment plan may not use the
full system/machine capability and thereby may not make use of the
system in the most efficient and reliable manner. The treatment
plan can be optimized for efficiency using a trial and error
methodology involving modification of several complex associated
plan parameters (e.g., energy layer distance, spot size or spot
spacing) required for multi-directional optimization. Even if an
optimized treatment plan finally passes the criteria for plan
quality and treatment delivery time, the application at the machine
may fail or may not achieve the optimal delivery efficiency as
requested by plan objectives during treatment planning due to
machine specific capability limitations of combined plan parameters
which are not taken into account by currently available commercial
treatment planning systems.
[0005] For example, in proton therapy treatment, a pencil beam is
scanned across the target area to deliver the radiation dose. The
scanning pattern goes line-by-line regardless of target shape or
time to deliver the field. FLASH therapy delivers ultra-high dose
rate treatment to a target and has been shown to reduce normal
tissue toxicity in preclinical studies. Little is known as to the
underlying biological mechanism behind the FLASH effect, but it is
postulated to have increasing benefits with increasing dose rate.
In pencil beam scanning (PBS), the dose rate becomes difficult to
define since each voxel dose rate is influenced by its neighbors. A
treatment planning system (TPS) is used to generate spots in a grid
pattern and to determine the dose of the spots. This information is
stored in a treatment plan that is executed by a proton therapy
treatment system (e.g., a gantry) that delivers the dose using
raster scanning.
[0006] Currently, the scanning pattern created by TPS is limited to
line-by-line scanning, and is typically optimized to minimize the
total dose received by the patient. Importantly, there is currently
no way to change or customize that pattern to optimize FLASH dose
rate delivery. Moreover, existing techniques for delivery of the
dose use standard scanning patterns that do not take into account
the dose rate, which can be problematic depending on the shape and
size of the target. For example, for a relatively large target,
scanning the target line-by-line may not be the most efficient
means to deliver the dose and can actually decrease the applied
dose rate dramatically. Therefore, standard scanning patterns are
often limited to lower dose rate, especially in the context of PBS
FLASH delivery. However, for high dosage rate treatments, such as
PBS FLASH therapy, it is desirable to maximize the dose rate
applied to normal tissue.
[0007] Therefore, an improved approach to FLASH treatment planning
is needed that can maximize the dose rate for different target
sizes, including relatively large targets, different shapes, and
different locations.
SUMMARY
[0008] Accordingly, embodiments of the present invention include an
improved approach to FLASH treatment planning that can maximize the
dose rate for FLASH treatment. More specifically, methods and
systems for proton therapy planning that maximize the dose rate for
different target sizes, shapes, and/or locations for FLASH therapy
treatment are disclosed herein according to embodiments of the
present invention. According to embodiments, non-standard scanning
patterns can be generated, for example, using a TPS optimizer, to
maximize dose rate and the overall FLASH effect for specific
volumes at risk. The novel scanning patterns can include scanning
subfields of a field that are scanned independently or
spiral-shaped patterns, for example. In general, spot locations and
beam paths between spots are optimized to substantially achieve a
desired dose rate in defined regions of the patient's body for
FLASH therapy treatment.
[0009] According to one embodiment, a system for proton therapy
treatment is disclosed. The system includes a gantry including a
nozzle configured to emit a controllable proton beam, a proton
therapy treatment system that controls the gantry according to a
treatment plan, and a treatment planning system including a memory
for storing image data and the treatment plan, and a processor
operable to perform a method of generating the treatment plan. The
method includes receiving imaging data of a target volume, dividing
the imaging data of the target volumes into a scanning pattern
including a plurality of subfields including a first scanning
direction and a second scanning direction, optimizing the scanning
pattern to achieve a desired dose rate, and outputting a treatment
plan including the scanning pattern. The treatment plan is operable
to instruct a proton therapy treatment system to perform proton
therapy treatment on the target volume according to the scanning
pattern, and the proton therapy treatment system, in accordance
with the treatment plan, scans in the first scanning direction at a
faster scanning rate and scans in the second scanning direction at
a slower scanning rate. The treatment plan is a proton therapy
treatment plan.
[0010] According to some embodiments, the method further includes
performing proton therapy treatment using the proton therapy
treatment system according to the optimized proton therapy
treatment plan.
[0011] According to some embodiments, the method further includes
receiving the desired dose rate as input.
[0012] According to some embodiments, the method further includes
determining the desired dose rate according to machine parameters
associated with the proton therapy treatment system.
[0013] According to some embodiments, the plurality of subfields is
scanned independently by the proton therapy treatment system.
[0014] According to some embodiments, the dividing the imaging data
of the target volume into a scanning pattern including a plurality
of subfields is performed based on a size of the target volume.
[0015] According to some embodiments, the desired dose rate is a
upper limit dose rate of the proton therapy treatment system.
[0016] According to another embodiment, a method of proton therapy
treatment is disclosed. The method includes receiving imaging data
of a target volume, dividing the imaging data of the target volume
into a scanning pattern including a plurality of subfields, the
plurality of subfields including a first scanning direction and a
second scanning direction, optimizing the scanning pattern to
achieve a desired dose rate, and outputting a proton therapy
treatment plan including the scanning pattern, the proton therapy
treatment plan is operable to instruct a proton therapy treatment
system to perform proton therapy treatment according to the
scanning pattern, and further the proton therapy treatment system
is operable to scan in the first scanning direction at a faster
scanning rate, and operable to scan in the second scanning
direction at a slower scanning rate.
[0017] According to some embodiments, the method includes
performing proton therapy treatment using the proton therapy
treatment system according to the proton therapy treatment
plan.
[0018] According to some embodiments, the method includes receiving
the desired dose rate as input.
[0019] According to some embodiments, the method includes
determining the desired dose rate according to machine parameters
associated with the proton therapy treatment system.
[0020] According to some embodiments, the plurality of subfields is
scanned independently by the proton therapy treatment system.
[0021] According to some embodiments, dividing the imaging data of
the target volume into a scanning pattern including a plurality of
subfields is performed based on at least one of: a size of the
target volume; a shape of the target volume; and a location of the
target volume.
[0022] According to some embodiments, the desired dose rate is an
upper limit dose rate of the proton therapy system.
[0023] According to a different embodiment, a method for proton
therapy treatment is disclosed. The method includes receiving
imaging data of a target volume of a patient, determining a size of
the target volume based on the imaging data, generating a scanning
pattern based on the size of the target volume, optimizing the
scanning pattern to reduce to a lower threshold limit an amount of
radiation received by healthy tissue of the patient, the scanning
pattern includes a substantially spiral-shaped scanning pattern,
and outputting a proton therapy treatment plan including the
scanning pattern, the proton therapy treatment plan is operable to
instruct a proton therapy treatment system to perform proton
therapy treatment according to the scanning pattern.
[0024] According to some embodiments, the method includes
performing proton therapy treatment using the proton therapy
treatment system according to the treatment plan.
[0025] According to some embodiments, the scanning pattern is
aligned to a grid-shaped pattern.
[0026] According to some embodiments, the scanning pattern is not
aligned to a grid-shaped pattern.
[0027] According to some embodiments, the proton therapy treatment
plan includes performing FLASH proton therapy.
[0028] According to some embodiments, the proton therapy treatment
system is configured for pencil beam scanning.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] The accompanying drawings, which are incorporated in and
form a part of this specification, illustrate embodiments of the
invention and, together with the description, serve to explain the
principles of the invention:
[0030] FIG. 1 shows a block diagram of an example of a computing
system upon which the embodiments described herein may be
implemented.
[0031] FIG. 2 is a block diagram showing selected components of a
radiation treatment system upon which embodiments according to the
present invention can be implemented.
[0032] FIG. 3 illustrates elements of a radiation treatment system
in accordance with embodiments of the present invention.
[0033] FIG. 4 is a block diagram illustrating components in a
process for creating an optimized proton therapy treatment plan and
scanning pattern in embodiments according to the present
invention.
[0034] FIG. 5A is a flow-chart depicting an exemplary sequence of
computer controlled steps for automatically creating an optimized
proton therapy treatment plan and scanning pattern to optimize dose
rate according to embodiments of the present invention.
[0035] FIG. 5B is a flow-chart depicting an exemplary sequence of
computer controlled steps for automatically creating an optimized
proton therapy treatment plan and scanning pattern to minimize the
amount of radiation received by healthy tissue according to
embodiments of the present invention.
[0036] FIG. 6A is a diagram of an exemplary proton therapy
treatment plan and standard scanning pattern.
[0037] FIG. 6B is a dose rate histogram of the exemplary proton
therapy treatment plan and standard scanning pattern depicted in
FIG. 6A.
[0038] FIG. 7A is a diagram of an exemplary proton therapy
treatment plan and optimized scanning pattern for increasing or
maximizing a dose rate applied to a target volume depicted
according to embodiments of the present invention.
[0039] FIG. 7B is a dose rate histogram of the exemplary proton
therapy treatment plan depicted in FIG. 7A in accordance with
embodiments of the present invention.
[0040] FIG. 8 is a diagram of an exemplary proton therapy treatment
plan and optimized scanning pattern for minimizing the amount of
radiation received by healthy tissue depicted according to
embodiments of the present invention.
DETAILED DESCRIPTION
[0041] Reference will now be made in detail to several embodiments.
While the subject matter will be described in conjunction with the
alternative embodiments, it will be understood that they are not
intended to limit the claimed subject matter to these embodiments.
On the contrary, the claimed subject matter is intended to cover
alternative, modifications, and equivalents, which may be included
within the spirit and scope of the claimed subject matter as
defined by the appended claims.
[0042] Furthermore, in the following detailed description, numerous
specific details are set forth in order to provide a thorough
understanding of the claimed subject matter. However, it will be
recognized by one skilled in the art that embodiments may be
practiced without these specific details or with equivalents
thereof. In other instances, well-known methods, procedures,
components, and circuits have not been described in detail as not
to unnecessarily obscure aspects and features of the subject
matter.
[0043] Portions of the detailed description that follows are
presented and discussed in terms of a method or process. Although
steps and sequencing thereof are disclosed in a figure herein
describing the operations of this method, such steps and sequencing
are exemplary. Embodiments are well suited to performing various
other steps or variations of the steps recited in the flowchart
(e.g., FIGS. 5A and 5B) of the figures herein, and in a sequence
other than that depicted and described herein.
[0044] The portions of the detailed description that are presented
in terms of procedures, steps, logic blocks, processing, and other
symbolic representations are of operations on data bits that can be
performed on computer memory. These descriptions and
representations are the means used by those skilled in the data
processing arts to most effectively convey the substance of their
work to others skilled in the art. A procedure, computer-executed
step, logic block, process, etc., is here, and generally, conceived
to be a self-consistent sequence of steps or instructions leading
to a desired result. The steps are those requiring physical
manipulations of physical quantities. Usually, though not
necessarily, these quantities take the form of electrical or
magnetic signals capable of being stored, transferred, combined,
compared, and otherwise manipulated in a computer system. It has
proven convenient at times, principally for reasons of common
usage, to refer to these signals as bits, values, elements,
symbols, characters, terms, numbers, or the like.
[0045] It should be borne in mind, however, that all of these and
similar terms are to be associated with the appropriate physical
quantities and are merely convenient labels applied to these
quantities. Unless specifically stated otherwise as apparent from
the following discussions, it is appreciated that throughout,
discussions utilizing terms such as "generating," "writing,"
"including," "storing," "transmitting," "traversing,"
"associating," "identifying," "optimizing" or the like, refer to
the action and processes of a computer system, or similar
electronic computing device, that manipulates and transforms data
represented as physical (electronic) quantities within the computer
system's registers and memories into other data similarly
represented as physical quantities within the computer system
memories or registers or other such information storage,
transmission or display devices.
[0046] Some embodiments may be described in the general context of
computer-executable instructions, such as program modules or
instructions, executed by one or more computers or other devices.
Generally, program modules include routines, programs, objects,
components, data structures, etc., that perform particular tasks or
implement particular abstract data types. Typically the
functionality of the program modules may be combined or distributed
as desired in various embodiments.
[0047] Novel Scanning Pattern Optimization for Flash Therapy
Treatment
[0048] The following description is presented to enable a person
skilled in the art to make and use the embodiments of this
invention; it is presented in the context of a particular
application and its requirements. Various modifications to the
disclosed embodiments will be readily apparent to those skilled in
the art, and the general principles defined herein may be applied
to other embodiments and applications without departing from the
spirit and scope of the present disclosure. Thus, the present
invention is not limited to the embodiments shown, but is to be
accorded the widest scope consistent with the principles and
features disclosed herein.
[0049] Methods and systems for proton therapy planning that
maximize the dose rate for different target sizes, shapes, and
locations for FLASH therapy treatment are disclosed herein
according to embodiments of the present invention. According to
embodiments, non-standard, novel scanning patterns can be
generated, for example, using a TPS optimizer, to maximize dose
rate and the overall FLASH effect for specific volumes at risk. The
novel scanning patterns can include scanning subfields of a field
that are scanned independently or may include spiral-shaped
patterns to achieve a desired dose rate and/or to minimize
radiation received by healthy tissue. In general, spot locations
and beam paths between spots are optimized in accordance with
embodiments of the present invention to substantially achieve a
desired dose rate in defined regions of the patient's body for
FLASH therapy treatment.
[0050] According to one embodiment, scanning pattern optimization
is performed by a TPS to generate a proton therapy plan that causes
a proton therapy system (e.g., a gantry) to scan a beam (e.g., a
pencil beam) faster in one direction compared to another direction
in order to increase or maximize the dose rate. By maximizing the
dose rate, the dose accumulation time for healthy tissue is
minimized. For example, for a relatively large target, sub-fields
of the target can be divided into oblong rectangular subfields, and
the treatment plan instructs the proton therapy system to scan the
long dimension of a rectangle at a faster predefined scanning rate,
and conversely, to scan the short dimension of the rectangular
subfields at a slower predefined scanning rate. The overall
size/area of a subfield (e.g., rectangle or rectangular subfield)
can be determined based on the desired dose rate that the optimizer
is attempting to achieve and/or a specified nozzle current, for
example. According to some embodiments, the scanning pattern is
optimized to increase or maximize the total biological FLASH effect
applied by the proton therapy system.
[0051] According to another embodiment, scanning pattern
optimization is performed by a TPS to generate a proton therapy
plan that causes a proton therapy system (e.g., a gantry) to scan a
beam (e.g., a pencil beam) in accordance with a scanning pattern
that minimizes the number of scans that are performed by the proton
therapy system that irradiate healthy tissue (e.g., healthy tissue
voxels). Generally a voxel in the beam path will receive a full
dose/dose rate, as well as some dose from the lateral penumbra of
adjacent beams, and these "extra" doses do not necessarily produce
a FLASH dose rate. Therefore, the scanning pattern optimization
performed by the TPS attempts to minimize the "extra" dose from
adjacent beams, which is especially critical in the context of
FLASH therapy for ensuring that the majority of healthy tissue
voxels only receive the healthy tissue dose rate specified by the
treatment plan.
[0052] Some embodiments optimize a primary scanning axis angle to
maximize dose rate by reducing the overall scanning time for a
given target shape and/or orientation, for example, based on
scanning magnet speed characteristics.
[0053] FIG. 1 shows a block diagram of an example of a computing
system 100 upon which the embodiments described herein may be
implemented. In a basic configuration, the system 100 includes at
least one processing unit 102 and memory 104. This most basic
configuration is illustrated in FIG. 1 by dashed line 106. The
system 100 may also have additional optional features and/or
functionality. For example, the system 100 may also include
additional storage (removable and/or non-removable) including, but
not limited to, solid state, magnetic or optical disks or tape.
Such additional storage is illustrated in FIG. 1 by removable
storage 108 and non-removable storage 120. The system 100 may also
contain communications connection(s) 122 that allow the device to
communicate with other devices, e.g., in a networked environment
using logical connections to one or more remote computers.
[0054] The system 100 also includes input device(s) 124 such as
keyboard, mouse, pen, voice input device, touch input device, etc.
Output device(s) 126 such as a display device, speakers, printer,
etc., are also included.
[0055] In the example of FIG. 1, the memory 104 includes
computer-readable instructions, data structures, program modules,
and the like. Depending on how it is to be used, the system 100--by
executing the appropriate instructions or the like--can be used to
implement a planning system used to generate a proton therapy plan
that causes a proton therapy system (e.g., a gantry) to scan a beam
(e.g., a pencil beam) faster in one direction compared to another
direction in order to increase or maximize the dose rate. For
example, for a relatively large target, sub-fields of the target
can be divided into oblong rectangular subfields, and the treatment
plan instructs the proton therapy system to scan the long dimension
of a rectangle at a faster predefined scanning rate, and to scan
the short dimension of the rectangles at a slower predefined
scanning rate. The scanning pattern of the proton therapy plan can
also be optimized to cause the proton therapy system to scan the
beam in a scanning pattern that minimizes the amount of radiation
received by healthy tissue. More generally, system 100 can be used
to generate and/or optimize proton therapy treatment plans in
accordance with the present invention.
[0056] FIG. 2 is a block diagram showing selected components of a
radiation treatment system 200 upon which embodiments according to
the present invention can be implemented. In the example of FIG. 2,
the system 200 includes an accelerator and beam transport system
204 that is operable to generate and/or accelerate a beam 201.
Embodiments according to the invention can generate and deliver
beams of various types including, for instance, proton beams,
electron beams, neutron beams, photon beams, ion beams, or atomic
nuclei beams (e.g., using elements such as carbon, helium, or
lithium). The operations and parameters of the accelerator and beam
transport system 204 are controlled so that the intensity, energy,
size, and/or shape of the beam are dynamically modulated or
controlled during treatment of a patient according to an optimized
radiation treatment plan produced by and stored within system 100
as discussed above.
[0057] A recent radiobiology study has demonstrated the
effectiveness of delivering an entire, relatively high therapeutic
radiation dose to a target within a single, short period of time.
This type of treatment is referred to generally herein as FLASH
radiation therapy (FLASH RT). Evidence to date suggests that FLASH
RT advantageously spares normal, healthy tissue from damage when
that tissue is exposed to only a single irradiation for only a very
short period of time. For FLASH RT, the accelerator and beam
transport system 204 can generate beams that can deliver at least
four (4) grays (Gy) in less than one second, and may deliver as
much as 40 Gy or more in less than one second. The control system
210 can execute a treatment plan for FLASH RT, and the plan can be
generated or optimized by system 100 executing an optimization
algorithm or procedure in accordance with embodiments of the
present invention.
[0058] The nozzle 206 is used to aim the beam toward various
locations (e.g., of a target) within a patient supported on the
patient support device 208 (e.g., a chair, couch, or table) in a
treatment room. A target may be an organ, a portion of an organ
(e.g., a volume or region within the organ), a tumor, diseased
tissue, or a patient outline, for instance.
[0059] The nozzle 206 may be mounted on or may be a part of a
gantry structure (FIG. 3) that can be moved relative to the patient
support device 208, which may also be moveable. In embodiments, the
accelerator and beam transport system 204 are also mounted on or
are a part of the gantry structure; in another embodiment, the
accelerator and beam transport system are separate from (but in
communication with) the gantry structure.
[0060] The control system 210 of FIG. 2 receives and implements a
prescribed treatment plan which is generated and/or optimized
according to embodiments of the present invention. In embodiments,
the control system 210 includes a computing system having a
processor, memory, an input device (e.g., a keyboard), and
optionally a display; the system 100 of FIG. 1 is an example of
such a platform for the control system 210. The control system 210
can receive data regarding the operation of the system 200. The
control system 210 can control parameters of the accelerator and
beam transport system 204, nozzle 206, and patient support device
208, including parameters such as the energy, intensity, size,
and/or shape of the beam, direction of the nozzle, and position of
the patient support device (and the patient) relative to the
nozzle, according to data the control system 210 receives and
according to the radiation treatment plan.
[0061] FIG. 3 illustrates elements of a radiation treatment system
300 for treating a patient 304 in accordance with embodiments of
the present invention. The system 300 is an example of an
implementation of the radiation treatment system 200 of FIG. 2, for
example. In embodiments, the gantry 302 and nozzle 306 can be moved
up and down the length of the patient 304 and/or around the
patient, and the gantry and nozzle can move independently of one
another. While the patient 304 is supine in the example of FIG. 3,
the invention is not so limited. For example, the patient 304 can
instead be seated in a chair or positioned in any orientation. The
gantry 302 can be controlled by a treatment system using an
optimized treatment plan generated according to embodiments of the
present invention.
[0062] With regard to FIG. 4, an exemplary proton therapy system
400 for imaging and treating a patient 304 is depicted according to
embodiments of the present invention. In the example of FIG. 4,
patient 304 is imaged using an image system 402 that uses, for
example, x-rays, magnetic resonance imaging (MM), and computed
tomography (CT). When CT or MM imagery, for example, is used, a
series of two-dimensional (2D) images are taken from a 3D volume
and stored in memory. Each 2D image is an image of a
cross-sectional "slice" of the 3D volume. The resulting collection
of 2D cross-sectional slices can be combined to create a 3D model
or reconstruction of the patient's anatomy (e.g., internal organs)
and stored in memory. The 3D model will contain organs of interest,
which may be referred to as structures of interest. Those organs of
interest include the organ targeted for radiation therapy (a
target), as well as other organs that may be at risk of radiation
exposure during treatment. According to some embodiments, the
imaging process is a separate process from the treatment planning
process, and the treatment planning process can include receiving
stored imaging data from a prior imaging session, for example.
[0063] One purpose of the 3D model is the preparation of a
radiation treatment plan. To develop a patient-specific radiation
treatment plan, information is extracted from the 3D model to
determine parameters such as organ shape, organ volume, tumor
shape, tumor location in the organ, and the position or orientation
of several other structures of interest as they relate to the
affected organ and any tumor. The radiation treatment plan can
specify, for example, how many radiation beams to use and which
angle from which each of the beams will be delivered.
[0064] In embodiments according to the present invention, the
images from the image system 402 are input to a planning system
404. In embodiments, the planning system 404 includes a computing
system having a processor, memory, an input device (e.g., a
keyboard), and a display. The system 100 of FIG. 1 is an example of
a platform for the planning system 404.
[0065] Continuing with reference to FIG. 4, the planning system 404
executes software that is capable of producing an optimized
treatment plan for treating patient 304. The treatment planning
system 404 can receive imagery data generated by image system 402
to implement a planning system used to generate a proton therapy
plan that causes the proton therapy system 300 to scan a beam
faster in one direction compared to another direction in order to
increase or maximize the dose rate, or to achieve a prescribed dose
rate 406 which can be optionally received as input by the planning
system 404. For example, for a relatively large target, sub-fields
of the target can be divided into oblong rectangular subfields, and
the treatment plan 408 instructs the proton therapy system to scan
the long dimension of a rectangle at a faster predefined scanning
rate, and conversely, to scan the short dimension of the rectangles
at a slower predefined scanning rate.
[0066] The scanning pattern of the proton therapy plan 408 can also
be optimized to cause the proton therapy system 300 to scan the
beam in a scanning pattern that minimizes the amount of radiation
received by healthy tissue. More generally, planning system 404 can
be used to generate and/or optimize proton therapy treatment plans
in accordance with the present invention. The treatment planning
system 404 outputs an optimized plan 408 according to an optimizing
algorithm. The optimized plan 408 is then used to configure
treatment system 300 for performing proton therapy treatment on
patient 304 using gantry 302, for example.
[0067] With regard to FIG. 5A, an exemplary sequence of computer
implemented steps 500 for automatically generating a proton therapy
treatment plan is depicted according to embodiments of the present
invention. The procedure 500 produces a proton treatment plan that
is optimized to increase or maximize a dose rate applied by a
proton therapy treatment system to normal/healthy tissue while
maximizing dose received by the target volume and minimizing the
dose received by normal tissue.
[0068] At step 501, imaging data of a target volume is received.
The image data can originate from computer memory or from a scan of
a target volume of a patient.
[0069] At step 502, imaging data of the target volumes is divided
into a scanning pattern including a plurality of subfields. The
subfields include a first scanning direction and a second scanning
direction.
[0070] At step 503, the scanning pattern is optimized to achieve a
desired dose rate.
[0071] At step 504, a proton therapy treatment plan is output
including the scanning pattern including a scanning methodology.
The proton therapy treatment plan is operable to instruct a proton
therapy treatment system to perform proton therapy treatment
according to the scanning pattern. The proton therapy treatment
system scans in accordance with the scanning methodology in which
scanning in the first scanning direction is performed at a faster
scanning rate, and conversely, scanning in the second scanning
direction is performed at a slower scanning rate.
[0072] According to some embodiments, a custom dose rate is
received as user input and is used as the desired dose rate.
[0073] According to some embodiments, the desired dose rate is
based on the maximum dose rate that can be produced by the proton
therapy system. The maximum dose rate and desired dose rate can be
determined according to machine parameters associated with the
proton therapy treatment system, for example. According to some
embodiments, the treatment planning system stores machine scanning
parameters in order to optimize a treatment plan for dose rate
(e.g., to maximize the dose rate for normal tissue). The machine
scanning parameters can include both a dose component and a timing
component. The dose rate can be maximized based on the timing
component and a desired dose.
[0074] With regard to FIG. 5B, an exemplary sequence of computer
implemented steps 550 for automatically generating a proton therapy
treatment plan is depicted according to embodiments of the present
invention. The procedure 550 produces a proton treatment plan that
is optimized to minimize a total dose received by health tissue of
a patient while treating a target volume.
[0075] At step 551, imaging data of a target volume is received.
The image data can originate from computer memory or from a scan of
a target volume of a patient.
[0076] At step 552, the size, shape, and/or location of the target
volume is determined based on computations involving the imaging
data.
[0077] At step 553, the scanning pattern is generated based on the
size, shape, and/or location of the target volume.
[0078] At step 554, the scanning pattern is optimized to minimize
an amount of radiation received by health tissue of the patient.
The scanning pattern may comprise a substantially spiral-shaped
scanning pattern.
[0079] At step 555, a proton therapy treatment plan is output
comprising the scanning pattern. The proton therapy treatment plan
is operable to instruct a proton therapy treatment system to
perform proton therapy treatment according to the scanning
pattern.
[0080] With regard to FIG. 6A, an exemplary proton therapy
treatment plan 600 including a standard scanning pattern 601
applied to a target volume (e.g., a tumor or organ) which is
surrounded by normal tissue for proton therapy treatment is
depicted. This treatment plan 600 is not optimized for PBS FLASH
delivery because the treatment plan 600 is generated using limited
optimization based on the total dose received by the patient. The
treatment plan 600 depicted in FIG. 6A may not use the full
system/machine capability (e.g., dose rate) because the treatment
plan 600 is generated to optimize total dose and does not consider
the dose rate. Therefore, the standard scanning patterns 601 are
limited to a lower dose rate than what is achievable using the
proton therapy system, which is especially disadvantageous in the
context of PBS FLASH delivery. As depicted in FIG. 6A, the
treatment plan is further constrained because the treatment spots
(represented by an `X` on the scanning pattern) must be aligned to
a grid-shaped pattern, and treatment spots cannot be placed between
the lines of the grid-shaped pattern. A more efficient approach for
FLASH treatment planning uses novel scanning patterns optimized in
accordance with the present invention to achieve higher dose rates,
as depicted in FIG. 7A.
[0081] FIG. 6B depicts a dose rate histogram 650 corresponding to
the exemplary proton therapy treatment plan 600 including the
standard scanning pattern 601 applied to a target volume depicted
in FIG. 6A. The dose rate achieved using the standard scanning
pattern 601 is relatively low (120 Gy/s) compared to the dose rate
achieved using scanning patterns of proton therapy treatment plans
optimized according to embodiments of the present invention.
[0082] With regard to FIG. 7A, an exemplary optimized proton
therapy treatment plan 700 is shown in accordance with the present
invention and suitable for PBS FLASH delivery. Treatment plan 700
includes optimized scanning pattern 701 that causes a proton
therapy system (e.g., a gantry) to scan a beam (e.g., a pencil
beam) faster in one direction compared to another direction to
advantageously achieve a relatively high dose rate. For example, in
the example depicted in FIG. 7A, the beam applied using optimized
scanning pattern 701 is scanned faster in the vertical direction
702 of rectangular subfield 703 than the horizontal direction 704
to optimize the dose rate applied by the proton therapy system.
According to some embodiments, the size/area of the subfield 703 is
determined based on a desired dose rate and/or a given nozzle
current. As depicted in FIG. 7A, the scanning pattern and the spots
applied align to a grid shaped pattern. However, it is appreciated
that the scanning pattern and the spots thereof can be freely
placed without conforming to a grid-shaped pattern, as depicted in
FIG. 8.
[0083] FIG. 7B depicts a dose rate histogram 750 corresponding to
the exemplary proton therapy treatment plan 700 including the
standard scanning pattern 701 applied to a target volume depicted
in FIG. 7A. The dose rate achieved using the standard scanning
pattern 701 is relatively high (310 Gy/s) compared to the dose rate
achieved using standard scanning patterns and is suitable for PBS
FLASH delivery.
[0084] With regard to FIG. 8, an exemplary optimized proton therapy
treatment plan 800 is shown including scanning pattern 801 that
causes a proton therapy system (e.g., a gantry) to scan a beam
(e.g., a pencil beam) to apply a desired dose rate and minimize the
amount of irradiation received by healthy tissue (e.g., healthy
tissue voxels). For example, in the example depicted in FIG. 8, the
beam is scanned in a spiral-shaped pattern to minimize the amount
of dose received by health tissue. According to some embodiments,
the size/area of the spiral-shaped pattern is determined based on a
desired dose rate, the size/shape of the target volume, and/or a
given nozzle current. As depicted in FIG. 8, the scanning pattern
and the spots applied are freely placed without conforming to a
grid-shaped pattern. In this way, the scanning pattern can better
conform to the size/shape of the target volume and can minimize the
amount of radiation received by healthy tissue.
[0085] Embodiments of the present invention, an improved approach
to FLASH treatment planning that can maximize the dose rate for
different target sizes, shapes, and locations including relatively
large targets, are thus described. While the present invention has
been described in particular embodiments, it should be appreciated
that the present invention should not be construed as limited by
such embodiments, but rather construed according to the following
claims.
* * * * *